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A coin is tossed twice and outcomes are recorded. If the random variable X represents the number of heads in the experiment, then the expectation of X will be:

Solution

✅ Correct Option: 2

When a coin is tossed twice, the possible outcomes are:

HH → 2 heads

HT → 1 head

TH → 1 head

TT → 0 heads

Total outcomes = 4 (all equally likely)

The random variable X represents the number of heads.


X can take values 0, 1, or 2.

P(X=0)=14P(X = 0) = \dfrac{1}{4} (only TT)

P(X=1)=24=12P(X = 1) = \dfrac{2}{4} = \dfrac{1}{2} (HT and TH)

P(X=2)=14P(X = 2) = \dfrac{1}{4} (only HH)


The expectation is calculated as:

E(X)=∑x⋅P(X=x)E(X) = \sum x \cdot P(X = x)

E(X)=0×14+1×12+2×14E(X) = 0 \times \dfrac{1}{4} + 1 \times \dfrac{1}{2} + 2 \times \dfrac{1}{4}

E(X)=0+12+12E(X) = 0 + \dfrac{1}{2} + \dfrac{1}{2}

E(X)=1E(X) = 1


Therefore, the expectation of X is 1.

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